Drive control arrangement for portable adding machines



y 1960 P. c. CHAMBERS 2,945,569

DRIVE CONTROL ARRANGEMENT FOR PORTABLE ADDING MACHINES Filed April 23, 1957 2 Sheets-Sheet 1 3H 8 INVENTOR.

PAUL C. CHAMBERS ATTORNEYS July 19, 1960 P. c. CHAMBERS 2,945,569

DRIVE CONTROL ARRANGEMENT FOR PORTABLE ADDING MACHINES Filed April 25, 1957 2- Sheets-Sheet 2 PAUL C. C-HAM B5125,

INVENTOR w fat'm,

ATroRNEY United States Patent DRIVE CONTROL ARRANGEMENT FORPOR ABLE ADDING MACHINES Paul C. Chambers, 210 S. PoplarSL, Charlotte, NC.

Filed Apr. 23,1957, Ser. No. 654,556

3 Claims. (Cl. 192-.02)

This invention relates to switch arrangements for closing an electrical circuit'to a motor and more particularly to a switch arrangement-for closing the circuit to the driving motor of a portable adding machine.

Heretofore, portable adding machines of various types have been provided with motor actuating switches which comprise pairs of cooperating switch contacts, one pair beingstationary, the other pair'being carried on the outer end of a mechanically actuated arm. Considerable difficultyhasbeen experienced by servicemen to properly'set the pairs of contact points so that the movable points contact the stationary points at the same time. It is of course well known that unless the contacts are'pro-perly set, the same will, soon burn or become pitted and necessitate their replacement in a very short period of time.

With the foregoing in mind, it is the primary object of this invention to provide a snap-action switch which has a single fixedcontact point and a single movable contact pointboth of which are built into the switch and require no adjustment or setting relative to each other after installation of the switch. The-use-d-f this simplified switch will greatly increase the period of time that an adding machine can be operated without the switch being replaced.

It is another object of-this invention to provide a new and greatly simplified arrangement --for'actuatin'g or closing the micro-switch.

It is a further object of t'he'inventionto provide a switch arrangement for a portable adding machine which may be replaced in a minimum amount oftime upon the switch becoming defective.

Some of the objects of the invention having-been stated, other objects will appear as the description proceeds when taken in connection with the accompanying drawings, in which-'- Figure 1 is a perspective view of the type ofportable adding machine to whichthe invention is applied;

Figure 2 is an enlarged side elevation, looking from the left side of Figure l, with apart of the casingb-roken away to show the novel switch arrangement;

Figure 3 is an enlarged fragmentary view of some of the elements shown in Figure 2;

Figure-4 is ahorizontal sectional view taken along line 4--4 of Figure 3 with some of 'the parts shown in plan;

Figure 5 is an exploded viewof the arrangement'of elements on the clutch control shaft for oontrolling'opera- 'tion of the motor; a

Figure 6 is a fragmentary vertical sectional view manually depressible keys 12, a tape 13 Jon whichnum ice bers are printed and the usual respective addition and subtraction motor'actuating bars 14 and 15.

Each time the bar 14 or 15 is pressed the adding machine 10 prints the set of'numbers, corresponding to the depressed numerical keys 12, on the tape 13 and completes a'computing .cycle through rotation of an electric motor 17 having a gear reduction unit housing, broadly indicated at 20, fixed on one end thereof(Figures 2, 3 and 4). The gear reduction unit housing 20 has an output drive-shaft21 mounted therein and connected to the usual calculating mechanism of the adding machine, not shown, and a single revolution clutch mechanism 22, inside the gear reduction housing 20, for driving the shaft 21. The clutch 22 (Figure 4) has one end of a'clutch stop arm 25 suitably connected thereto and the free end of which is adapted'-to, at times,-engage a releasing cut-out portion 26 on a clutch control rod 27. The control rod '27 is ,oscillatably mounted in the gear reduction unit housing 20 (Figures '4 and 6) and *whenmoved to the position shown in Figure6, in a manner to be later described, will stop rotation'of the stop arm 25 and shaft 21.

The addition and subtraction motor actuating bars 14 and 15 are suitably connected, in a conventional manner, not shown, to one end of a motor actuating shaft 30, on the opposite end of which one end of a motor actuating lever 31 is fixed. The free end of the motor actuating lever 31, when raised by depressing the bar '14 or 15,

engages a pin 32 (Figures 4 and 5) fixed in one end of an arm "33 of a holding lever 34. The holding lever 34 is "fixed on the end of the clutch control rod 27 by a taper pin whichpenetrates the rod '27 and a boss integral with the lever 34. Theholding lever 34 is also provided with a stop arm 35 and is normally urged in a counterclockwise direction, in Figures 2 and 3, by a tension spring 37, one end of which is fixed on a spring perch 40 in the holding lever 34-and the opposite end of which is mounted on a pin 41 fixed on the gear reduction unit housing 20.

The holding lever 34 has a switch actuating arm 42 adjustably secured thereto which has a bent portion or tail 43 overlying and at'times engageablewith a resilient switch arm 45 of a normally open snap-action electric switch ,50. 'The switch actuating arm 42 is slidably mounted on the boss of the holding lever 34 and is ad justably secured to the holding lever 34 by a locking plate 55 slidably mounted on the boss of the holding lever 34. The plate 55 is adapted to receive an eccentric collar 56 which penetrates the plate 55 and engages a notch 57 in the switch actuating arm 42 and the coller 56 is mounted on a screw 58 which is'threadably embedded in the arm 33 of the holding lever 34. The position of the arm 42 maybe adjusted, relative to the pins 32, by loosening the screw 58, rotating the eccentric 56 to move the arm 42,

and tightening the screw 58 to lock the arm 42 against the lever 34 in adjustedposition.

The end of'the stop arm 35 is adapted to, at times, engage a stop member 60 mounted intermediate the ends of a'knock-oif lever 61, one end of which is oscillatably mounted on a stud 62 fixed in the gear reduction unit housing 2 0. The free end of the knock-ofi lever 61 is provided with a stop portion 63 adapted to, at times, engage thepin 41 on which the tension spring 37 is mounted. The knock-off lever 61 is normally urged to the'position shown in Figure 3 'by a tension spring 64, one end of which is fixed on the knock-ofi lever as at 65 and the other end of which is suitably secured to 'the gear reduction unit housing 20 as at 66. The knock-off lever 61 is provided with a knock-off pin 70 which is, at times, engaged by a high surface 71 on a knock-01f cam 72 fixed on the output drive shaft 21 (FiguresS and 4).

The sensitive electric switch 50' is preferably of the type manufacture'di by Micro Switch, a division of First Industrial Corporation, Freeport, Illinois, under their model No. BZ-RL. This invention is not limited to use of the particular switch described but may be used with other types which produce a snap-action and have a single set of contact points. The switch 50 has a pair of electrical wires 75 and 76 connected to opposite ends thereof which are a part of an electrical circuit to the motor 17 so that the electrical circuit will be completed to the motor 17 when the switch arm 45 is lowered by the switch actuating arm 42 engaging the same as shown in Figure 3. The electrical circuit to the motor 17 also includes lead wires 77 and 78 which are connected to any suitable source of electrical energy, not shown.

The switch 50 is mounted on a mounting plate 80 as by screws 81 and the plate 80 is suitably secured to a spaced governing bracket 82 as by screws 83. The speed governing bracket 82 pivotally supports the medial portion of a speed governing switch arm 83a the upper end of which is adapted to be actuated by a conventional governor 84 fixed on the end of the driving shaft of the electric motor 17. The governor 84 is provided with centrifugally operated weight members 85 connected to an actuating pin 86 engageable with the upper end of the switch arm 83a. The lower end of the switch arm 83:! is provided with an electrical contact 87. The contact 87 (Figure 4) is engageable with a contact 88 mounted on the bracket 82 and the contacts 87 and 88 are connected in the electrical circuit with the switch 50 and the electrical motor 17 so that the switch 50 and contacts 87 and 88 must be closed for the motor 17 to operate at full speed. The contacts 87 and 88 are connected to the electrical circuit by respective wires 87a and 88a (Figures 3 and 4) with the wire 87a being connected to the switch arm 83 and current being carried through the switch arm 33a to the contact 87.

In the event the motor 17 speeds up beyond a desired speed, the weight members 85 will be thrown outwardly, by centrifugal force, to move the pin 86, to the right in Figure 3, and pivot the switch arm 83a, in a clockwise direction, and cause the electrical contact member 87 to be moved away from the contact 88 to cause the current to be passed through an electrical resistor 90 and reduce the amount of current directed to the motor 17 so that the speed of the motor 17 will be reduced. The full amount of current will again be directed to the motor 17 when the speed of the governor 84 is reduced by the switch arm 83a moving in a counterclockwise direction to close the contacts 87 and 88. The resistor 90 acts to regulate the amount of current passing through the motor 17 to prevent continuous operation of the governor 84- after the motor 17 has become heated with continued operation.

In an addition or subtraction cycle ofthe adding machine it), the desired keys 12 are pushed and then either the addition bar E4 or the subtraction bar 15 is depressed to actuate the motor 17 and print the figures corresponding to the depressed keys 12 on the tape 13 and add or subtract the figures to the accumulated total. Both of the bars 14 and 15 are connected, by conventional linkage, not shown, to the motor actuating shaft 30, and

upon downward movement of either of the bars 14 or 15, the shaft 30 will be moved in a counterclockwise direction in Figures 2 and 3 to raise the free end of the lever 31 from substantially the position shown in Figure 2, to contact the pin 32 on the holding lever 34 and move the holding lever 34, clutch control rod 27 and switch actuating arm 42 to the positions shown in Figure 3 so that the switch arm 45 Will be moved downwardly by the tail portion 43 on the arm 42 and complete the circuit through the electric switch 50 to the electric motor 17 to rotate the motor 17. At the same time that the holding lever 34 is moved, to the position shown in Figure 3, the knock-off lever 61 will be pulled, to the position shown in Figure 3, by the spring 64 so that the end of the stop arm 3'5 of the holding lever 34 engages the stop member thereon to hold the clutch control rod 27, holding lever 34, switch actuating arm 42 and plate 55 in the position shown in Figure 3 until released by the knock-off cam 72 although the bar 14 or 15 may be released immediately and the shaft 38 and lever 31 returned to the position shown in Figure 2. Thus, even if either the bar 14 or 15 is depressed only momentarily the motor 17 will make a complete revolution to complete a calculating cycle of the machine.

With rotation of the motor 17 and upon rotation of the clutch control rod 27 so that the notch 26 will be moved in a clockwise direction (Figure 6) the clutch stop arm 25 will rotate in a clockwise direction so that the clutch member 22 will impart rotation to the output drive shaft 21. With rotation of the output drive shaft 21, the knock-ofi cam 72 will be rotated in a clockwise direction (Figure 3) and upon the high portion 71 thereof engaging the knock-off pin 70 on the knockoif lever 61, the lever 61 will be moved in a clockwise direction so that the stop 60 thereon will move out of engagement with the end of the stop arm 35 of the hold ing lever 34. The holding lever 34 will then be released so that the spring 27 will return the holding lever 34, switch actuating arm 42 and clutch control rod 27 to the position shown in Figure 2 to allow the switch arm 45 to be raised and the switch 50 to return to its normally open position and break the electrical circuit to the motor 17 as the clutch stop arm 25 engages the clutch contact rod 27.

Since the opening and closing of the contact points 87 and 88 is controlled by the speed governor 84 and the contact points 87 and 88 are connected in series with the switch 50, any time that the switch 50 is closed to impart rotation to the electric motor 17, the speed governor 84 will control the speed of the electric motor 17.

It is thus seen that an improved mechanism for starting a calculating cycle in a portable adding machine has been provided which includes a snap-action, enclosed switch having a long operating life and where no adjustment or setting of points is required as has been heretofore required with the two point adjustable contact switch previously used. An improved and simplified arm for actuating the switch has also been provided. This improved switch and actuating arm may be applied to portable adding machines without any changes to the structure of the adding machine, electrical wiring, or operation thereof.

In the drawings and specification there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

I claim:

1. In a portable adding machine having an electric actuating motor, a gear reduction unit connected to said electric motor, an output drive shaft on said reduction unit operatively connected to the calculating mechanism of said adding machine, a one revolution clutch in said gear reduction unit, manually operable means for activating said one revolution clutch to transmit rotation from said motor to said output drive shaft, knock-off means actuated by rotation of said output drive shaft to disengage said one revolution clutch and stop rotation of said output drive shaft upon completion of one revolution, the combination therewith of a switch actuating arm operatively connected at one end to said manuallyoperable clutch operating means, an electrical snap-action switch, a switch operating plunger in said switch normally resiliently urged to the open position, a switch arm mounted on said switch and engaging said plunger, said switch actuating arm and said switch arm being in parallel rela tionship to each other with the switch actuating arm being .norrnally positioned in spaced relation above the switch arm, the free end of said switch actuating arm being bent at a right angle to overlie said switch arm, and said switch actuating arm engageable with said switch arm upon operation of said manually operable clutch operating means to close said snap-action switch and complete an electrical circuit to said electric motor.

2. In a portable adding machine having an electric drive motor, a one revolution clutch drivingly connected to said electric drive motor, a rotatable clutch control rod controlling operation of said one revolution clutch, a holding lever fixed at one end to said clutch control rod and extending outwardly therefrom, manually operable means adapted to engage and move said holding lever to rotate said clutch control rod in a first direction to activate said one revolution clutch, knock-off means adapted to engage and move said holding lever to rotate said clutch control rod in a second direction and disengage said one revolution clutch, the combination therewith of a switch actuating arm fixed at one end to said clutch control rod and extending outwardly therefrom in a direction opposite from said holding lever, an electrical snap-action switch controlling operation of said motor, said switch actuating arm being normally positioned in spaced relation above said switch and movable into engagement with said switch to close the same upon rotation of said clutch control rod in said first direction, and said switch actuating arm being movable out of engagement with said switch to open the same upon rotation of said clutch control rod in said second direction.

3. In a portable adding machine having an electric drive motor, a one revolution clutch drivingly connected to said electric drive motor, a rotatable clutch control rod controlling operation of said one revolution clutch, a

holding lever fixed at one end to said clutch control rod and extending outwardly therefrom, manually operable means adapted to engage and move said holding lever to rotate said clutch control rod in a first direction to activate said one revolution clutch, knock-off means adapted to engage and move said holding lever to rotate said clutch control rod in a second direction and disengage said one revolution clutch, the combination therewith of a switch actuating arm fixed at one end to said clutch control rod and extending outwardly therefrom in a direction opposite from said holding lever, an electrical snap-action switch controlling operation of said motor, a switch operating plunger in said switch normally resiliently urged to the open position, a switch arm mounted on said switch and engaging said plunger, said switch actuating arm being normally positioned in spaced relation above said switch arm and movable into engagement with said switch arm to close the switch upon rotation of said clutch control rod in said first direction, and said switch actuating arm being movable out of engagement with said switch arm to open the switch upon rotation of said clutch control rod in said second direction.

References Cited in the file of this patent UNITED STATES PATENTS 

